Fabric anti-twisting device for circular knitting machines

ABSTRACT

A DEVICE FOR MINIMIZING THE TWISTING OF FABRIC PRODUCED ON CIRCULAR KNITTING MACHINES. THE DEVICE UTILIZES AN INNER PERFORATED EXTENSION OF THE FABRIC TUBE THROUGH WHICH THE FABRIC NORMALLY PASSES. THE EXTENSIN IS ROTATABLY MOUNTED ON THE FABRIC TUBE AND SUBJECT TO A VACUUM IN ORDER TO DOWNWARDLY TENSION THE FABRIC AS IT IS KNITTED. THE LOWER END OF THE FABRIC TUBE EXTENSION IS CLOSED WITH AN OPENABLE COVER OR DISC WHICH IS ALSO ROTATABLY MOUNTED. THE ROTATION OF THE PERFORATED FABRIC TUBE, EXTENSION, AND COVER AT THE SAME RATE OF SPEED AS THE KNITTING MACHINE HEAD AVOIDS TWISTING OF THE KNITTED FABRIC. MEANS TO PNEUMATICALLY EJECT THE KNITTED FABRIC ARE ALSO PROVIDED.

Feb. 23, 1971 c. A. FOREMAN 3,564,875

FABRIC ANTI-TWISTING DEVICE FOR CIRCULAR KNITTING MACHINES Filed Aug. 29. 1969 f 1 li; 2 46 [5 L 22 a i 1 :4 P i: i 45 SE 2 1) \q (g1 .0 lo

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ATTORNEYS United States Patent Office 3,564,875 Patented Feb. 23, 1971 3,564,875 FABRIC ANTI-TWISTING DEVICE FOR CIRCULAR KNITTING MACHINES Caley A. Foreman, Grenada, Miss., assigmor to US.

Industries, Inc., New York, N.Y., a corporation of Delaware Filed Aug. 29, 1969, Ser. No. 854,155 Int. Cl. D04b 15/88 US. Cl. 66-149 7 Claims ABSTRACT OF THE DISCLOSURE A device for minimizing the twisting of fabric produced on circular knitting machines. The device utilizes an inner perforated extension of the fabric tube through which the fabric normally passes. The extension is rotatably mounted on the fabric tube and subject to a vacuum in order to downwardly tension the fabric as it is knitted. The lower end of the fabric tube extension is closed with an openable cover or disc which is also rotatably mounted. The rotation of the perforated fabric tube, extension, and cover at the same rate of speed as the knitting machine head avoids twisting of the knitted fabric. Means to pneumatically eject the knitted fabric are also provided.

This invention relates to devices used in conjunction with circular knitting machines and particularly with devices used for minimizing twisting of fabrics knit by the circular knitting machines.

A serious problem has arisen in using standard circular knitting machines for the production of stockings having greater lengths than had been manufactured heretofore. This problem is that of the detrimental fabric twisting caused by the incompatibility of the lengthened fabric with standard knitting machine heads. This difficulty is pronounced in making panty hose where two stockings of waist length (as with panty hose) are used. An additional difficulty arises when loose knit yarns are utilized which are to be subsequently crimped to produce a stretch yarn. The lose knit yarn, being substantially longer than the final crimped fabric, causes similar twisting of the fabric.

The take-01f device in circular knitting machines is designed to permit rotation of the knitted fabric with the needle cylinder at all times. When the take-up carriage drops to its lower limit, additional fabric length will cause twisting of the fabric. In a vacuum take-up, twisting will occur when the longer fabric begins to accumulate on the floor of the vacuum tube. In addition, there is likely to be some twisting caused by air or fabric tube friction even on machines not equipped with take-up facilities.

Attempts at solution of this problem by elevating the knitting head to provide a greater distance from machine floor to knitting head, or by installing fabric tubes of larger diameter to permit the fabric to balloon out to foreshorten the fabric, have met with only limited success. In both instances, fabric tube friction or air friction, or both, still tend to cause the fabric to lag behind the rotation of the needle cylinder and therefore to cause twisting of the fabric.

It is an object of the present invention to provide a device for the minimization of fabric twisting in circular knitting machines.

In accordance with the present invention, a tubular fabric anti-twisting device for a circular knitting machine comprises a perforated interior fabric tube adapted to interiorly receive, guide and rotate with the fabric descending from the machine to and through the fabric tube. Carrier means are provided openably closing the lower discharge end of the fabric tube, the carrier means being adapted to rotate with said tube and to selectively open or close the discharge end of the tube. Also included are a sealed stationary casing surrounding the fabric tube and carrier means; a vacuum conduit operatively connected to the casing, fabric ejection means connected to the conduit adapted to produce an airflow from the interior of the fabric tube through the perforations into the casing Whereby the tubular fabric is tensioned downwardly in said tube, and means for repositioning the carrier means relative to the fabric tube to open the tube, and pass the fabric to the ejection means.

For a better understanding of the present invention together with other and further objects thereof, reference is made to the following detailed description, taken in conjunction with the accompanying drawings, the scope of the invention being set forth in the appended claims.

In the drawing, the single figure is a partially schematic fragmentary vertical cross-sectional view of a conventional circular knitting machine, modified in accordance with the present invention.

Referring to the figure, shown are portions of a conventional circular knitting machine designated 10, having a needle cylinder 11 carrying needles 12 and the usual sinker ring 13 and sinkers 14. The machine includes a transfer dial jack 15 carrying transfer jacks (not shown). The needle cylinder 11 and transfer dial 15 are synchronously driven by appropriate gearing including bevel gear 17 and bevel gear 18.

A fabric tube 20, adapted to interiorly receive, guide and rotate with the descending fabric, is mounted Within the needle cylinder 11 by appropriate means which typically includes spacer ring 16. The spacer ring 16 centers the fabric tube 20 and causes the fabric tube to rotate in synchronism with needle cylinder 11. The fabric, as it is produced by the needles 14, enters the fabric tube 20 at the top.

The fabric tube 20 includes a mechanically connected fabric tube extension 40. This extension 40 is a perforated cylinder connected to the fabric tube by suaging, force fitting, welding or other appropriate means, so that it may rotate with the fabric tube. The fabric tube 20 including extension 40 form an inner cylinder rotatably mounted with a sealed stationary casing or outer supporting cylinder 41. The volume Within outer cylinder 41 is subject to a vacuum as Will be described later.

The outer cylinder 41 is supported by outer cylinder clamp 39 which is attached to a frame member for centering and stability. The upper portion of the outer cylinder is additionally supported by bearing clamp 22 which also serves as a centering ring. Anti-friction ball bearings 21 with ply seals are disposed between the top of the outer cylinder 41 and the fabric tube. The ball bearings allow friction-reduced rotation of the fabric tube 20 relative to the outer cylinder 41. The ply seals are necessary to seal the vacuum within the outer cylinder 41.

The lower end of the fabric tube extension 40 is closed by carrier means shown as disc 25. The disc openably closes the lower discharge end of the fabric tube extension 40. The disc is fastened to piston rod 26 by means of anti-friction bearings. Disc 25 forms the floor of the fabric tube extension and rotates with it thus supporting the fabric in contact with its surface. Means are provided for repositioning the disc relative to the fabric tube to open the tube, by lowering piston rod 26, which selectively opens or closes the discharge end of the fabric tube extension.

At the bottom of the outer cylinder is the outer cylinder lower ring 24 which serves as a vacuum seal for the outer cylinder and as a mount for air cylinder 27.

Connected to an opening 23 in the stationary outer cylinder is a vacuum conduit, which includes tube 47 and a conventional vacuum take-down butterfly assembly 42, for the purpose of providing a vacuum within the outer cylinder.

Fabric ejection means are connected to tube 47 and are adapted to produce an airflow from the interior of the fabric tube extension 40 through the perforations into the outer cylinder so that the tubular fabric is downwardly tensioned in the tube. These ejection means include a compressed air line which feeds air cylinder 27 and an inlet for compressed air 28 in tube 47 conventionally called a blow-up.

Tube 47 has a pivoted top 45 which is normally held closed by the applied vacuum. The top of the vacuum take-down butterfly assembly 46 is the exit for the fabric.

The device is operated in the following manner. During knitting, vacuum is applied through the vacuum takedown assembly 42. The compressed air lines are depressurized and disc 25 forms the floor of the fabric tube extension 40 as the disc rotates with the tube. As the fabric is knitted, the applied vacuum draws the fabric downwardly through the fabric tube, the direction of airflow being from inside the fabric tube extension 40 through the perforations into the outer cylinder 41. The fabric accumulates on disc 25 which is rotating at the same speed as the fabric tube and needle cylinder. Thus, no twist is applied to the fabric, since all parts in frictional contact with the fabric are essentially motionless relative to the fabric.

When, for example, a stocking is completed, a jet of compressed air is applied to compressed air line 47. The compressed air is directed to air cylinder 27 which acts upon piston rod 26 to lower disc 25 to its lowered position 25A. The lower end of the fabric is thus freed and it approaches outer cylinder opening 23.

A jet of compressed air is also applied to blow-up 28. This compressed air jet opens the pivoted top 45 of the vacuum take-down assembly and at the same time draws the stocking through tube 47 and propels it through exit 46. At this point the stocking can go to any desired collector system such as a bag or storage container.

The device described is very simple to manufacture, is trouble-free in operation and represents a major economic breakthrough. Not only has the twisting problem been avoided by the present invention, but the majority of parts used in conventional vacuum ejection circular knitting machines has been preserved to accomplish the desired result. The present invention thereby obviates purchasing new machines or extensive restructuring of old machines to avoid the twisting problem in knitting extralength fabrics.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein, with out departing from the invention, and it is therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A tubular fabric anti-twisting device for a circular knitting machine comprising:

a perforated interior fabric tube adapted to interiorly receive, guide and rotate with the fabric descending from said machine to and through said tube;

carrier means openably closing the lower discharge end of said fabric tube, said carrier means being adapted to rotate with said tube and to selectively open or close the discharge end of said tube;

a sealed stationary casing surrounding said fabric tube and carrier means;

a vacuum conduit operatively connected to said casing;

fabric ejection means connected to said conduit adapted to produce an airflow from the interior of said fabric tube through said perforations into said casing whereby the tubular fabric is tensioned downwardly in said tube; and

means for repositioning said carrier means relative to said fabric tube to open said tube, and pass said fabric to said ejection means.

2. A device as described in claim 1 wherein said perforated fabric tube is rotatably mounted within said casing with anti-friction bearings having vacuum seals between said tube and casing.

3. A device as described in claim 1 wherein said carrier means includes a disc rotatably mounted with antifriction hearings on a piston rod.

4. A device as described in claim 1 wherein said conduit is connected to said casing at a position below the normally closed position of said carrier means and above the normally open position of said carrier means.

5. A device as described in claim 1 wherein said conduit includes a normally closed pivoted exit cover and a vacuum take-down butterfly assembly.

6. A device as described in claim 1 wherein said fabric ejection means includes a compressed air line supplied to said vacuum conduit.

7. A device as described in claim 1 wherein said means to open said tube includes a compressed air line, an air cylinder subject to pressure from said air line and a piston rod mounted in said air cylinder and connected to said carrier means, said piston rod lowering said carrier means to open said tube as said compressed air pressure is applied.

References Cited UNITED STATES PATENTS 2,972,875 2/1961 St. Pierre 66149SUX 3,063,275 1l/l962 Luchi 66149S 3,267,698 8/1966 Poteat 66149S 3,443,403 5/1969 Thore 66149S 3,479,842 11/1969 Baird 66149S 3,516,268 6/1970 Foreman 66149S FOREIGN PATENTS 558,876 3/1957 Italy 66149S ROBERT R. MACKEY, Primary Examiner 

